Genetic Risk Found For Elevated Arsenic Toxicity

     An article from Medical News Today on February 25, 2012 referred to a study that was published in PLos Genetics. The study discovered genetic variants that raised the risk for skin lesions in people that are chronically exposed to the chemical arsenic. There were genetic changes found near the enzyme that metabolizes the chemical into a less toxic form, it can greatly increase a person's risk  for developing an arsenic-related disease.

     The study was conducted on 3,000 people in Bangladesh who had been exposed to arsenic for decades. Arsenic poisoning is a big problem in developing countries. The study focused on arsenic-related diseases, such as skin lesions, diabetes, and respiratory illness. It was found that the person's dose or duration of exposure to the chemical did not matter, each individual's reactions differed, some show toxicity phenotypes while others do not.

    Reasearchers genotyped the 3,000 individuals for single nucleotide polymorphism(SNPs) throughout their genome and they looked for a relationship between arsenic metabolite levels and the risk for skin lesions. After ingestion of arsenic, the body metabolizes the chemical into monomethylarsonic acid(MMA) first, and then into dimethylarsinic acid(DMA). MMA is very toxic, while DMA is not and it is easily excreted. High levels of DMA in a person's urine was associated with lower toxicity from the chemical. This then led to the finding of several genetic variants that are located in the same area as the likely candidate gene: Arsenite Methyltransferase (As3MT). As3MT is an enzyme that is essential in metabolizing arsenic. These genetic findings provide evidence that efficient metabolism of arsenic through methylation protects the person from the chemical.

     Compounds that are known to boost methylation, such as folic acid, could be used to reduce arsenic toxicity. These findings are very significant and can hopefully help put an end to what the World Health Organization calls "the largest mass poisoning of a population in history".